This invention relates to a dried emulsion process for introducing additives into ceramic materials so as to obtain particular properties in ceramic bodies made from those materials.
It is common practice in manufacturing electronic ceramics to incorporate additives into the ceramic body to obtain certain desirable properties in the finished material These additives may shift the Curie temperature to a higher or lower value; they may promote grain growth or inhibit it; they may help to adjust and control the temperature coefficient of capacity; they may serve as a flux and lower the sintering temperature. The variables involved are not all independent of one another, and a single additive will frequently function in more than one mode. These additives are added in small amounts, frequently as little as 1 or 2% of the total ceramic weight, and only rarely in excess of 5% of the ceramic weight.
These additives are commonly added in the prior art as calcined oxides. Where the major ceramic components are present as fine particle ceramics in our ceramic paints it is essential that all additives used also be in fine particle form. This is necessary to ensure adequate mixing and a uniform, homogeneous structure in the final ceramic matrix. It is possible to follow the teachings of Cipollini in U.S. Pat. No. 4,654,075 and our above-identified parent application Ser. No. 947,117 (issued June 7, 1988 as U.S. Pat. No. 4,749,664) to prepare these additives in fine powder form.
It is an object of this invention to provide a process for introducing additives into fine powder ceramic materials which offers better chemical control and significant savings in cost.
It is an object of this invention to provide a process for introducing additives into fine powder ceramic materials in other than calcined oxide form.
Another feature of this invention is to provide a process for introducing additives into fine powder ceramic materials in the form of precursors of the additives.